I originally spotted this as an Almost AIC where either 6r3c4 or 6r9c4 if 6r4c5.
If 6r9c4 then AIC: (8=6)r4c5-r5c4=r9c4-(6=1)r9c6-r5c6=1r5c5 => -8r5c5
If 6r3c4 then Almost Element: 6r3c4-(67=2)r23c6-r1c6=r1c2-(2=6)r3c1 Conflict => -6r3c4
Thus the AIC is valid to complete the puzzle.